/*
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 * and open the template in the editor.
 */

package mythinking;

/**
 *
 * @author jzou
 */


import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class DomParserExample {

	//No generics
	List myEmpls;
	Document dom;


	public DomParserExample(){
		//create a list to hold the employee objects
		myEmpls = new ArrayList();
	}

	public void runExample() {

		//parse the xml file and get the dom object
		parseXmlFile();

		//get each employee element and create a Employee object
		parseDocument();

		//Iterate through the list and print the data
		printData();

	}

	public String getEmployeesInfo() {

		//parse the xml file and get the dom object
		parseXmlFile();

		//get each employee element and create a Employee object
		parseDocument();

		//Iterate through the list and print the data
		return getData();

	}


	private void parseXmlFile(){
		//get the factory
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

		try {

			//Using factory get an instance of document builder
			DocumentBuilder db = dbf.newDocumentBuilder();
            // InputStream is = ClassLoader.getSystemResourceAsStream("ServletStateless.resources.employees.xml");
            InputStream is = getClass().getResourceAsStream("employees.xml");
			//parse using builder to get DOM representation of the XML file
      		// dom = db.parse("ServletStateless/resources/employees.xml");
            dom = db.parse(is);


		}catch(ParserConfigurationException pce) {
			pce.printStackTrace();
		}catch(SAXException se) {
			se.printStackTrace();
		}catch(IOException ioe) {
			ioe.printStackTrace();
		}
	}


	private void parseDocument(){
		//get the root elememt
		Element docEle = dom.getDocumentElement();

		//get a nodelist of <employee> elements
		NodeList nl = docEle.getElementsByTagName("Employee");
		if(nl != null && nl.getLength() > 0) {
			for(int i = 0 ; i < nl.getLength();i++) {

				//get the employee element
				Element el = (Element)nl.item(i);

				//get the Employee object
				Employee e = getEmployee(el);

				//add it to list
				myEmpls.add(e);
			}
		}
	}


	/**
	 * I take an employee element and read the values in, create
	 * an Employee object and return it
	 * @param empEl
	 * @return
	 */
	private Employee getEmployee(Element empEl) {

		//for each <employee> element get text or int values of
		//name ,id, age and name
		String name = getTextValue(empEl,"Name");
		int id = getIntValue(empEl,"Id");
		int age = getIntValue(empEl,"Age");

		String type = empEl.getAttribute("type");

		//Create a new Employee with the value read from the xml nodes
		Employee e = new Employee(name,id,age,type);

		return e;
	}


	/**
	 * I take a xml element and the tag name, look for the tag and get
	 * the text content
	 * i.e for <employee><name>John</name></employee> xml snippet if
	 * the Element points to employee node and tagName is name I will return John
	 * @param ele
	 * @param tagName
	 * @return
	 */
	private String getTextValue(Element ele, String tagName) {
		String textVal = null;
		NodeList nl = ele.getElementsByTagName(tagName);
		if(nl != null && nl.getLength() > 0) {
			Element el = (Element)nl.item(0);
			textVal = el.getFirstChild().getNodeValue();
		}

		return textVal;
	}


	/**
	 * Calls getTextValue and returns a int value
	 * @param ele
	 * @param tagName
	 * @return
	 */
	private int getIntValue(Element ele, String tagName) {
		//in production application you would catch the exception
		return Integer.parseInt(getTextValue(ele,tagName));
	}

	/**
	 * Iterate through the list and print the
	 * content to console
	 */
	private void printData(){

		System.out.println("No of Employees '" + myEmpls.size() + "'.");

		Iterator it = myEmpls.iterator();
		while(it.hasNext()) {
			System.out.println(it.next().toString());
		}
	}

	private String getData(){
        StringBuffer sb = new StringBuffer();

		sb.append("No of Employees '" + myEmpls.size() + "'.");

		Iterator it = myEmpls.iterator();
        sb.append("\n<ul>\n");
		while(it.hasNext()) {
			sb.append("<li>" + it.next().toString() + "</li>\n");
		}
        sb.append("</ul>\n");
        
        return sb.toString();
	}


	public static void main(String[] args){
		//create an instance
		DomParserExample dpe = new DomParserExample();

		//call run example
		// dpe.runExample();
        System.out.println(dpe.getEmployeesInfo());
	}

}
